The lateral decubitus breast boost: description, rationale, and efficacy.

Area of Science:

• Radiation Oncology
• Medical Physics
• Breast Cancer Treatment

Background:

• Electron boost irradiation is crucial for optimizing tumor bed coverage in breast cancer.
• Traditional positioning may lead to suboptimal electron beam penetration and increased skin dose.
• A modified technique aims to improve target volume coverage and reduce radiation-related side effects.

Purpose of the Study:

• To describe and evaluate a modified lateral decubitus boost technique for breast irradiation.
• To assess the impact of repositioning on electron beam depth and target coverage.
• To evaluate patient tolerance and skin reactions associated with this technique.

Main Methods:

• A retrospective review of 2,606 breast irradiation patients, with 231 undergoing resimulation in the lateral decubitus position for electron boost.
• Measurement of skin-to-target depth in original and repositioned plans.
• Evaluation of patient demographics (age, BMI), electron energy, and skin reactions.

Main Results:

• Resimulation in the lateral decubitus position reduced average skin-to-target depth by 2.12 cm, enabling an average electron energy reduction of 7 MeV.
• Mean skin entrance dose decreased from approximately 90% to 85% (p < 0.001).
• Only 6% of patients experienced moist desquamation; higher BMI (>30) correlated with greater depth reduction and increased desquamation risk.

Conclusions:

• The lateral decubitus position effectively decreases skin-to-target depth, enhancing electron coverage of the breast tumor bed.
• This technique reduces skin entrance dose and is well-tolerated, particularly for patients with high BMI or deep tumor locations.
• The modified lateral decubitus boost offers an improved approach to electron boost radiation therapy for select breast cancer patients.